“” Meat allowed the human species to develop “,” Iron and vitamin B12 intakes were essential to brain development ” : These sentences, you have certainly heard them. They are not entirely false, but not totally true either, Other factors enter the equation.
A study published on January 16 in the journal Science has just given us very interesting data who come to confirm this theory more. Australopithecus fossils (potential ancestors of modern humans who lived approximately 4 to 2 million years ago) found in the caves of Sterkfontein, South Africa, delivered precious information on their food mode. How ? Thanks to microscopic traces preserved on their dental enamel.
The first meals of humanity
To manage to unravel the secrets of the food regime of our most distant ancestors, the researchers of the laboratories of the Max Planck Institute for Chemistry and the University of Witwatersrand have developed a specific technique. This is based On nitrogen isotopesthese variations of the same element that accumulate differently depending on the diet.
They thus analyzed the ratio between two forms of nitrogen: the 15n and the 14n, which act as molecular tracers. The more an animal consumes meat, the more the proportion of 15n increases in its tissues, leaving an indelible chemical imprint of its eating habits. By analyzing the relationship between isotopes 15n and 14n in fossil dental enamel, scientists can therefore Determine the position of the individual in the food chain.
Until then, paleontologists had to be content to analyze the collagen of the bones or the dentin, tissues which deteriorate over the millennia. It was impossible to go back beyond 300,000 years Due to this degradation, which formed a real completely opaque veil, which blurred the analysis of ancient diets. The dental enamel being the most resistant fabric of the body of mammals, it preserves these isotopic signatures as a coded message crossing ages and thanks to it, it is possible to trace millions of years of food evolution.
Australopithecus: not really Viandards
To decode what had to tell us about the seven fossils found, scientists organized a vast comparative studyfeaturing a whole prehistoric bestiary. Monkeys, antelopes or other predators such as hyenas, jackals and great felines. Each species was the equivalent of a different link in the food chain three million years ago.
It turns out that the isotopic signatures inscribed in the dental enamel of the Australopithecus prove that they mainly ate Foods from vegetable sources. Their teeth bear the chemical imprint of a diet where plants dominated, with only a few rare episodes of meat consumption. The traces found bring them much more closer to peaceful herbivores than predators of their time.
While the scientific community had long seen in the consumption of meat the main engine of human brain development, reality is much more nuanced. It also means that the behaviors observed in Australopithecus – their ability to use rudimentary tools, their complex social life – do not only find their origin in a meat diet.
The great history of rewritten human evolution
For Dr Dominic Stratford, director of this research, The conclusion is clear : ” This study unequivocally demonstrates that the Australopithecus of South Africa did not consume notable quantities of meat three million years ago. It constitutes a major advance in our ability to analyze food regimes and the position of species in the food chain on a scale of several million years ».
Our evolutionary history is therefore enriched by a new chapter. If our distant South African ancestors favored plants, the regular adoption of a carné diet would have occurred later in our evolutionary historyor in another geographic region.
This is why we must consider today; even more in the light of this study; that the development of human cognitive capacities as The result of multiple interactions. Other elements have probably contributed together to the gradual increase in the size of the brain observed in more recent hominids. Social factors (group life, cultural transmission), genetics (mutations, natural selection) or linked to lifestyle (manufacturing of tools, control of fire).
The adoption of meat by our ancestors was progressive and was an evolutionary response to climate upheavals occurred about 2.5 million years ago in Africa. While lush forests gradually gave way to arid savannas, the first representatives of the genre Homo (1 to 1.5 million years after Australopithecus) needed to diversify their diet in the face of the scarcity of plant resources.
The tired stone tools, which appeared around 2.6 million years, first allowed charging and then, later, hunting, which allowed them to access more easily meat resources. This food transition has triggered a series of physiological adaptations: anatomical modifications with the reduction of jaws and teeth, evolution of the digestive system, but also deep social transformations where the sharing of meat has catalyzed new cooperative behaviors. However, this study shows us that this new diet mode was not the only determining factor in this progressioneven if he has undoubtedly played an important role in the evolution of Australopithecus towards the Homo sapiens.
- An analysis of the dental enamel of Australopithecus revealed that they had an essentially vegetable diet, with very little meat consumption.
- Contrary to popular belief, meat has not been the only engine of human brain development, other factors such as group life and the use of tools have also played a key role.
- The gradual introduction of meat in the diet of the first Homo was a necessary adaptation, but this study comes to question its central role in cognitive evolution.
